The conventional combination lock may be turned to open it while listening or feeling it with sensitive fingertips. This is possible when there is a certain amount of play among the working parts of the lock; by listening intently and pulling on the spindle, the tally of the notch on each combination wheel and the projection on the spindle of the shackle can be felt.
The present inventor has found this defect of conventional combination lock and invented the present improved locking device of combination lock.
The present invention is described in details in the following specification with reference to the enclosed drawings.